In the commonly assigned, copending U.S. patent application Ser. No. 351,629, filed Feb. 23, 1982, of one of us, Bode, there are shown and described several embodiments of modular conveyor belting molded of synthetic plastic material. In many of the embodiments, the belting modules which are hinged together by plastic rods, are designed to be able to negotiate horizontal turns, i.e. lateral turns, within the plane of the support surface of the belting. An embodiment particularly designed for straight-running without horizontal turns is disclosed in that application with reference to FIGS. 19 and 20 of that application. Common to the design of all of the belt module embodiments of Ser. No. 351,629 are pintles which have transverse slots that are oversize with respect to the rods which are received through the slots to pivotally interconnect longitudinally adjoining belt modules and unite transversally adjoining belt modules. On the straight-running belts, the oversize slots are configured to permit the pintle, slot and pin regions of the belt to be readily cleaned.
An important commercial use of such conveyor belt made of modules that are molded of synthetic plastic resin, is in transporting rather small objects along a processing line through several stations or at least from one station to another. The small objects may be loose, e.g. fresh green beans being transported through a blanching station to a freezer, or they may be bottles or other containers of a product, e.g. small recently-lidded jars of jam being conveyed through a washing station.
A typical way of collecting objects at the end of a conveyor run is to juxtapose a support surface level with the downstream end of the conveyor run. Where the objects to be accepted from the conveyor are large the support surface may be constituted by a simply-configured dead plate. However, especially where the objects to be collected are small, it is generally necessary to provide a set of fingers on the upstream margin of the stationary support surface, which fingers intercalate with the conveyor belt structure so as to provide a transfer comb for more gradually and smoothly transferring support of the objects from the moving belt to the stationary support surface, or to another conveyor.
Where small objects are to be transported by a conveyor that is molded of synthetic plastic material, an especially challenging structural design problem has existed in the art, which in the view of the present inventors has heretofore gone unsolved by any commercially marketed conveyor belt system. The problem has seemed inherent: that if support features were made thin and closely spaced, modules were potentially short-lived and difficult to keep clean, but if they were thickened and more widely spaced, small objects were poorly supported due to the size of gaps between support features and there was a lack of flatness in the support surface. In addition, the belt-module/sprocket interface has presented a structural design problem: when sprocket teeth drive against connecting rods and module hinges, stress concentrations may cause modules, hinges and sprockets to be short-lived and belt tracking to be unstable.